A common set-up for the administration of intravenous fluids to a patient, such as saline solution to which medication may have been added, includes a drip chamber connected to a catheter which extends to the patient. A valve below the drop chamber controls the rate of administration of the fluid to the patient. In some situations, such as in critical care environments, it may be necessary to closely control the rate at which fluid is administered to the patient over an extended period of time. While the common set-up involves simple disposable items, it does not permit close control of the rate of administration of the fluid to the patient. An apparatus which enables the administration of fluid over an extended period of time, wherein the parts which contacted the fluid were of low cost to permit them to be disposable, would be of considerable value. In such an apparatus, any power required to operate it should be derived primarily from pressured air which is commonly available in a hospital and which avoids the possibility of electrical shocks from electric power outlets.